Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/02—Making granules by dividing preformed material
  • B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
  • B29B9/065—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion under-water, e.g. underwater pelletizers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S425/00—Plastic article or earthenware shaping or treating: apparatus
  • Y10S425/23—Hay wafering or pelletizing means

Definitions

• the present invention generally relates to improvements in underwater pelletizers and more particularly to providing a sectioned adjustable water flow guide for the water box of an underwater pelletizer to more effectively adapt the conditions associated with the pressurized water flowing through the water box to the particular process requirements.
• the present invention provides for adjustability of the one-piece water flow guide disclosed in co-pending application, Serial No. 09/400,287, filed September 21, 1999, which is owned by the same assignee as the instant application.
• the flow guide in the aforesaid application is shown positioned in a typical Model 6 pelletizer of assignee.
• the subject matter of the aforesaid co-pending application is specifically incorporated in this application as if fully set forth herein.
• Underwater pelletizers are well known and include a die plate with multiple orifices through which molten polymer strands are extruded with the orifices terminating at a die face on the die plate.
• a powered rotary cutter including a cutter hub mounted on a shaft with a plurality of blades supported from the cutter hub is associated with the die face for shearing the extruded polymer strands into pellets as the polymer is extruded beyond the die face.
• a water box encloses the die face, cutter hub and blades to form a cutting chamber through which water flows to quench and rigidify the extruded polymer strands, thus enabling the cutting blades to better shear the extruded strands into pellets.
• the flow of water through the cutting chamber defined by the water box also conveys a slurry of the water and sheared pellets through the outlet of the water box to a pellet dewaterer and/or a dryer.
• the above described underwater pelletizers are disclosed in related U.S. patents including U.S. Patent Nos. 4,123,207, 4,251,198, 4,621,996, 4,728,276 and 5,059,103, all owned by the assignee of this invention.
• Another object of the present invention is to provide an adjustable water flow guide that optimizes pellet distribution and generates satisfactory head pressure against the pellets through water flow control .
• a further object of the present invention is to provide a sectioned water flow guide stationarily positioned in the cutting chamber of an underwater pelletizer hat can be adjusted to effectively vary the amount of cutting chamber space for successful pellet generation.
• Still another object of the present invention is to provide a water flow guide that directs water to the seal area and, through circulation within the internal flow guide chamber, eliminates fines incoming thereto, pumping such fines immediately out of the seal area to prevent interference with the rotating shaft .
• a still further object of the present invention is to provide a water flow guide made of multiple interchangeable sections which, through selection of the number and thickness of the sections used, can effectively accommodate a broad range of melt temperatures, pellet sizes, cutter speeds and water temperatures in the pelletizing operation.
• Yet another object of this invention to be specifically enumerated herein is to provide a water flow guide in accordance with the preceding objects which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide a device that will be economically feasible, long lasting and relatively trouble free in operation.
• the water flow guide of the present invention is sectioned and thus adjustable in length so that, when positioned within the cutting chamber defined by the water box of an underwater pelletizer, the flow of pressurized water passing through the water box can be changed in accordance with the adjusted size selected for the water flow guide .
• the overall length of the flow g ⁇ ide can be selectively modified, and the amount and rate of water allowed to flow past the face of the die plate can be adjusted.
• the water flow guide of this invention is stationarily mounted within the cutting chamber, preferably on the front of the pelletizer, and is oriented in the cutting chamber between the water inlet and the water and pellet slurry outlet of the water 'box, which are typically disposed in diametrically opposed relation, such as a water inlet at the bottom of the cutting chamber and the water and pellet slurry outlet at the top.
• the adjustability of the water flow guide can produce a range of pressurized water flows and effectively direct a specified volume of cooling water toward the die face and the polymer strands being extruded therefrom. By varying the distance between the cutting blades and the flow guide to direct and control the water flow to the die face, excessive cooling of the polymer and associated distortion of the pellets is prevented.
• the adjustable water flow guide of the present invention optimizes pellet distribution, improves the initial cooling effect of the pellets, and generates satisfactory head pressure against the pellets, allowing the flow of water across the face of the die plate to be optimized in accordance with the needs of specific pelletizing applications.
• the water flow guide is in the form of a cylindrical tubular member affixed to the pelletizer in generally concentric relation to the rotating shaft of the pelletizer, preferably with the body of the guide filling out the majority of the. cutting chamber volume.
• the free end of the guide's tubular member preferably terminates adjacent to the rotating cutter hub and cutting blades mounted thereon.
• the water flow guide is a generally cylindrical tubular member with the external surface thereof being disposed adjacent to the generally cylindrical inner surface of the water box, preferably with a very small clearance therebetween.
• the tubular member includes a generally cylindrical axial bore which is positioned over and surrounds the rotating cutting hub shaft forming an annular space therebetween. Between the tubular member and the pelletizer, a variable number of annular sections can be positioned to adjust the overall length of the flow guide and thereby alter the flow volume passing over the face of the die plate for any particular application.
• the water flow guide is made up of a plurality of sections which together form a generally cylindrical tubular member with an outer wall, again, preferably sized to be only slightly smaller than the inner wall of the water box to provide a very small clearance between the adjacent surfaces.
• Each section is machined to fit in close abutment with its adjacent section or sections and, when joined, the sections create a cylindrical outer surface that includes diametrically opposed, axially extending recesses, with one recess in alignment with the water inlet and the other recess in alignment with the slurry outlet of the water box.
• One end of each of the axial recesses is spaced between the ends of the cylindrical surface and in registry with the water inlet and slurry outlet, respectively.
• each of the axial recesses opens to a free end of the water flow guide which terminates facing the cutter hub and cutter blades .
• Sections of different thicknesses may be employed to adjust the overall length of the flow guide and the axial recesses .
• the axial recess portion of each section is properly machined to retain the continuity of the desired overall axial recess when the sections are adjoined.
• the water flow guide again includes the generally tubular ' cylindrical member formed of sections as described in the second embodiment .
• the cylindrical member is formed of a plurality of annular flat plates that are bolted together. Because there are no recesses machined therein, this embodiment has simplified manufacturing requirements, while still effectively providing a means for adjusting water flow through the cutting chamber.
• the adjustability of the flow guide enables a wider range of water temperatures, melt- temperatures, flow rates and pellet sizes to be accommodated simply by selecting the desired flow guide components.
• Figure 1 is a vertical, ' longitudinal sectional view of an underwater pelletizer having one embodiment of a water flow guide with annular sections positioned therein in accordance with the present invention, and illustrating the water flow path through the cutting chamber. .
• Figure 2 is a transverse, vertical sectional view along section line 2-2 in Figure 1 illustrating the association of the water flow guide to the water box, pelletizer drive shaft, cutter hub, water inlet and water and slurry outlet.
• Figure 3 is a perspective view of the water flow guide with annular sections shown in Figures 1 and 2 looking at the end adjacent the die plate, cutter hub and cutter blades.
• Figure 4A is a perspective view of a variant of the water flow guide with annular sections of Figures 1-3.
• Figure 4B is an exploded view of the annular sections and variant water flow guide shown in Figure 4A.
• Figure 5A is a second embodiment of a flow guide in accordance with the present invention, the flow guide formed of multiple adjoining sections.
• Figure 5B is an exploded view of the multiple section water flow guide shown in Figure 5A.
• Figure 6 is a vertical longitudinal sectional view of an underwater pelletizer having a third embodiment of an adjustable water flow guide mounted in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS
• FIGS 1-3 illustrate a water flow guide, generally designated by reference numeral 10, associated with an underwater pelletizer, generally designated by reference numeral 12.
• the underwater pelletizer 12 such as that disclosed in U.S. Patent No. 5,059,103, is a typical Model 7 pelletizer manufactured by the assignee of this application.
• the pelletizer 12 is schematically illustrated and includes a die plate 14 having a plurality of die orifices 16 therein through which molten polymer is extruded into strands which pass through a die face 18 on the inner surface of the die plate 14.
• the die plate 14 is connected to a pelletizer water box, generally designated by reference numeral 20, which includes a cutting chamber 22 and also includes a pressurized water inlet 24 and a diametrically opposed outlet 26 for discharge of a slurry of water and pellets from the cutting chamber 22 for conveyance out of the water box 20 to a pellet dewaterer and/or a pellet dryer (not shown) .
• the pelletizer 12 includes a motor 28 with an output shaft 30 drivingly connected to a cutter hub shaft 32 having a cutter hub 34 mounted thereon.
• the cutter hub 34 includes a plurality of radially extending support arms 36 which support replaceable cutter blades 37 which coact with the die face 18 to shear the extruded strands of polymer into pellets.
• the structure of the underwater pelletizer may correspond generally with that disclosed in U.S. Patent No. 5,059,103 or any other known configuration and design.
• the typical underwater pelletizer utilizes water to cool and rigidify the strands of polymer as they are discharged from the die face, with the spacing of the cutter blades and the rotational speed of the cutter hub determining the size of pellets sheared from the extruded polymer strands. Water flowing in through the water inlet not only cools and rigidifies the polymer strands but also conveys the sheared pellets as a slurry from the cutting chamber into the outlet .
• the water flow guide 10 of the present invention guides the inlet water from inlet 24 toward the die plate 14 so that it moves along the surface of the die face 18 and over and around the rotating cutter hub 34 and cutter blades 37.
• the cutting chamber space and selectively directing this water flow the extruded strands of polymer may be more efficiently quenched, thereby more effectively cooling and rigidifying the polymer strands.
• the size of the flow guide and thus the water flow space inside the cutting chamber the flow of too much water across the die face can be prevented, thereby reducing pellet distortion and die hole freezing.
• the water flow guide 10 also provides -more effective entrainment of the pellets in the water and more effective conveyance of the water and pellet slurry through the flow path for discharge through outlet 26 from the water box 20 for subsequent dewatering and drying.
• the water flow guide illustrated in Figures 1-3 includes, a generally cylindrical tubular member, generally designated by the reference numeral 38, having an outer surface 40 and a cylindrical axial bore 42 which is substantially concentric with and closely surrounds the drive shaft 32 as illustrated in Figure 1, thus forming an annular space 43.
• Interchangeable annular sections 60, 62 are mounted to the pelletizer end of the cylindrical tubular member 38 which is furthest from the die plate. An outermost section 62 abuts and is secured against the seal holding plate 46 to which the flow guide is mounted.
• the seal holding plate 46 is provided with an annular rubber-type seal 44 which prevents inflow of the water circulating in the annular space 43 between the axial bore 42 and drive shaft 32.
• the number of annular sections 60, 62 may be varied, as may the thickness of each section, to allow the overall length of the flow guide to be adjusted, thereby providing a means for increasing or decreasing the flow of water across the face of the die plate. When too much water flows across the die face, the pellets can become distorted and the die holes can freeze over.
• various numbers of annular sections e.g., one, two, three, etc., as well as the use of sections having different thicknesses, the water flow is increased or decreased according to specific application requirements. Because the annular sections may be readily manufactured out of stainless steel, the resulting -flow guide also demonstrates reduced deterioration arising from pellet wear in the flow inlet and outlet, extending the useful life of the flow guide.
• the free end 48 of the cylindrical member 38 is flat with a tapered or beveled edge 56 around its periphery.
• the free end 48 terminates adjacent the cutter blades 37 on the cutter hub 34.
• a plurality of longitudinally extending through-bolts 50 are countersunk into the flat surface 48 of the tubular member 38 and extend therethrough and through the annular sections 60, 62 to screw thread into the seal holding plate 46 of the pelletizer structure. Bolts of different lengths may be employed depending upon the number of annular sections inserted between the flow guide and the pelletizer.
• the tubular cylindrical member 38 with the annular sections 60, 62 is rigidly affixed to the pelletizer and is oriented in concentric relation to the cutter hub shaft 32, with the external surface 40 adjacent the interior surface of the cutting chamber 22.
• the external surface 40 of the cylindrical member 38 includes diametrically opposed longitudinally extending grooves, or recesses 52 which are arcuate in transverse configuration.
• the grooves or recesses 52 are in alignment with the diametrically opposed water inlet 24 and slurry outlet 26, respectively.
• the inner end of each recess 52 is preferably arcuately curved at 54 so that the outer edge of the upwardly curved inner end coincides with the interior surface of the aligned edge of each the water inlet 24 and the slurry outlet 26, respectively.
• the outer end of each recess terminates at the free outer end 48 and beveled edge surface 56 which faces the rotational path of the cutter blades 37, as illustrated in Figures 1 and 3.
• Other recess formation and passageway designs may be machined into the various sections, such as those shown and described in aforesaid co-pending U.S. patent application, Serial No. 09/400,287.
• the external surface 40 of the guide is closely adjacent or engaging the internal surface of the cutting chamber 22 and the flat surface 48 is closely adjacent the cutter hub 34 and cutter blades 37 with sufficient clearance not to interfere with their rotation.
• the guide 10 preferably fills the whole cutting chamber 22.
• the close fitting relationship of the water flow guide 10 in relation to the water box 20 and cutting chamber 22 assures that incoming pressurized water will engage the axial recess 52 in alignment with the water inlet 24, causing the .water to move axially toward the die face 18, the cutter hub 34, cutter hub arms 36 and cutter blades 37, and then transversely across the die face 18 and around the cutter hub assembly.
• the transverse flow of water across the die face 18 may be optimized for any given pelletizing application and pellet size.
• the design of the water flow guide also facilitates water flow through the annular space or chamber 43, moving incoming fines out of the area adjacent the seal 44, to prevent such fines from packing into the annular space 43 around the shaft 32.
• FIGS 4A and 4B illustrate a variant of the water flow guide shown in Figures 1-3, generally designated by the reference numeral 70.
• Flow guide 70 includes tubular member 72 having an internal axial bore 74, an external axial recess 76 for alignment with pressurized water inlet and a diametrically opposed external axial recess 78 for alignment with a water and pellet slurry outlet.
• the free end of the water flow guide 70 is provided with opposing beveled or sloped edge surfaces 80, and a tapering sloped relief 82 is provided on each edge surface 80 in opposing angular directions on the free end of the water flow guide, to facilitate water flow.
• through-bolts 84 pass through apertures in the tubular member 72 and apertures 86 in the annular sections 88, 89 to mount the flow guide to the pelletizer in substantially the same position in the water box.
• FIGs 5A and 5B illustrate a second embodiment of the water flow guide, generally designated by the reference numeral 90, which includes a plurality of sectioned pieces 92, 94, 96, 98 which are bolted together to form a tubular member as illustrated in Figure 5A.
• the rearwardmost section 98 is generally cylindrical without cutouts in its outer surface.
• the next adjacent section 96 has a generally spherical section cutout 107 to define the back end of axial grooves 110 which correspond to surface 54 and axial grooves 52, respectively, in the first embodiment.
• the two front sectioned pieces 92, 94 have circular cutout openings 102, 104, respectively, which, when the sectioned pieces are bolted together, mate with cutout 107 to form the axial grooves 110, as in the first embodiment.
• each of sectioned pieces 92, 94, 96 includes a pair of axial recesses 103, 105, 107, respectively, the recesses of each pair being in opposing relationship.
• axial recesses 103, 105 are substantially equal in size and shape
• axial recesses 107 are arcuately curved (spherical section shaped) so that the outer edge ' of the upwardly curved inner end coincides with the interior surface of the aligned edge of each of the water inlet 24 and the slurry outlet 26, respectively.
• each of sectioned pieces 92, 94, 96 could include only one recess, or the sectioned pieces could be manufactured without any recesses.
• Figure 6 depicts a cross-sectional view of a third embodiment of a water flow guide in accordance with the present invention, generally designated by the reference numeral 110, as mounted to an underwater pelletizer.
• the flow guide 110 is comprised of a plurality of pieces, here annular flat plates 112, 114, 116, 118 that include generally oval openings 128 through which bolts may be inserted to secure the plates to each other and to the seal holding plate 120.
• the plates can be machined with ' inlet and outlet grooves on their outermost surfaces to direct the water flow or, as shown in Figure 6, can be made without grooves.
• a holding plate seal 122 fits into a groove on the surface of the seal holding plate 120 to prevent entry of the water circulating within the annular space 124.
• Flow of water through the annular space 124 acts to move incoming fines immediately out of the seal area, preventing the accumulation of such fines around the shaft 33 which might otherwise interfere with the. seal 122 and shaft 33 rotating therein.
• the nature and density of the fines define the final configuration of the flow guide and the desired spacing between axial bore wall 119 of the flow guide 110 and the pelletizer shaft 33. Varying numbers of plates may be included to adjust the overall length of the resulting flow guide.
• each additional plate narrows the inflow channel 24A for water flowing from the inlet 24 and the outflow channel 26A through which the slurry is directed, as well as the overall cutting chamber space. Varying the number of plates also enables the distance between the cutter hub holder and blades and the flow guide to be adjusted in order to optimize pellet distribution, improve the initial cooling effect of the water on the pellets and generate satisfactory head pressure against the pellets leaving the die holes .
• the adjustable flow guide greatly reduces the need for different water box designs in order to alter inlet and outlet flow configuration.
• the adjustable flow guide now provides a means of customization of water flow while using the same water box. Different effects may also be obtained with the same cutter hub design through adjustment in the flow guide .
• the present invention enables head pressure, which is the result of the design of the pelletizing system after the pellets are introduced into the water flow, to be adjusted across a broader range.
• the adjustable water flow guide enables important parameters including pipe dimension and length, height, extra pressure valve and water flow, also to be adjusted easily and efficiently.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
• Catching Or Destruction (AREA)
• Farming Of Fish And Shellfish (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

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• 2002
  • 2002-10-29 US US10/282,095 patent/US6925741B2/en not_active Expired - Fee Related
• 2003
  • 2003-10-29 ES ES03779392T patent/ES2283844T3/es not_active Expired - Lifetime
  • 2003-10-29 AT AT03779392T patent/ATE358007T1/de active
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  • 2003-10-29 WO PCT/US2003/034236 patent/WO2004039550A1/en active IP Right Grant
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